Symptoms
- Pop-ups appear even with no browser open
- Ads show on sites that normally don't have them
- Fake virus warnings urging you to call a number or download software
- New toolbar or search engine you didn't install
Likely causes
- CommonAdware browser extensionA free extension or app bundled adware that injects ads and pop-ups.
- CommonMalicious website redirectSome sites trigger fake system alerts through the browser itself.
- CommonNotification permission granted to a spammy siteClicking 'Allow' on a site's notification prompt lets it push ads like system alerts.
- PossibleAdware installed alongside other softwareBundled installers sometimes add unwanted programs unless you opt out.
- Less commonGenuine malware infectionMore aggressive pop-ups combined with slowdowns can indicate deeper infection.
What to do
- Do not call any phone number or download anything a pop-up tells you to; close the tab or browser instead.
- Check browser notification settings and remove permissions for any sites you don't recognize.
- Review installed browser extensions and remove any you don't remember installing.
- Check your computer's installed programs list for unfamiliar recent installs and uninstall them.
- Run a full scan with your operating system's built-in security tool (Windows Security or macOS's built-in protections) or a reputable malware scanner.
- Reset the browser to default settings if pop-ups continue.
- Change important passwords afterward if you may have entered any into a fake page.
When to call a pro
If pop-ups persist after cleanup, or you entered payment/personal info into a fake alert, get help from a trusted computer repair professional.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.